Process of recovering sodium, potassium and magnesium chlorides from natural brines



, POTASSIUM, AND

TURAL BRINES MAGNESIUM CHLORIDES FROM NA INVENToR.

' /4TToRNEx/s.

Filed July 5, 1929 '-15 Utah salt brines.

Patented June 2l, 1932 UNITED STATES Prem" OFFICE i HERMAN B. KIPPER, OF N EW YORK, N. Y. Y

PROCESS OF RECOVERING SODIUM, POTAKSSUM AND MAGNESIITM CHLORIDES FROM NATURAL BRINES Application filed July 5,

The present invention relates to a method of sepa-rating the chlorides of sodium, potassium and magnesium from brines suchas those obtained from the Great Salt Lake 5 desert and which contain principally the above named chlorides in solution in about 1.25% of the latter two salts and 18% for the sodium salt. The solution is practically saturated with the said sodium salt.

I am fully conversant with the methods employed in securing potassium and magnesium chlorides from the Strassfurth deposits and also the many methods hitherto used for the recovery of these salts from However, the ineliiciency of the foregoing processes is common knowledge. Y

To overcome the aforementioned drawback I have developed a process for recovery of said salts, which constitutes the subject of my invention.

This process is based on the counter current heat principle. At one end of the apparatus employed for carryingout my new process, v the liquid or brine used is heated practica-ly to the boiling point or just below such temperature, and at the other end thereof arti- `ticial cooling is used-whereby the brine temperature is reduced to about 0 C. The respective liquors or brines in a counter current fashion are made to gradually give off their heat or to cool one another down as required, by either direct or indirect action on one another. i Y

By this process the separation of the salts of the brines is accomplished in a highly cid cient manner.

brief description of the process for the. separation oit the sodium, potassium and magnesium chlorides from one another when contained in the same solution or brine follows. The present description applies more particularly to a brine of the nature ot Utah salt brine or at least the concentrations ot this brine. However the methods are, of course, of general application.

As potassium and magnesium are the two valuable constituents of the Utah brines and as these are not in a saturated condition in 59 the said brine, the latter is lirst evaporated 1929. Serial No. 375,908.

by solar evaporation, i. e. by use of the heat from the sunl and bv use of the winds etc. up to a point where it becomes saturated with potassium chloride.` v

In order to render the ground employed for solar' evaporation mpre impervious, I 'first treat the same with an alkali or alkaline solution,as ammonium hydroxide, lime water, sodium n hydroxide, sodium carbonate,` etc. In this manner part of the magnesium chloride with which the ground is largely saturated is converted to a. magnesium hydroxide or other basic magnesium salt. This forms magnesium cementatious materials, as the well known magnesium Oxy-chloride cement. g5

rlhe ground is thereby rendered very nonporous or impervious to water or to the .brines in question. f

During this primary evaporation eighty to ninety percent of the sodium chloride or common salt, are precipitated out and aboutthe same percentage of water is evaporated or eliminated from the process. The brine then contains about 120 to 130 grammes per liter of potassiumchlorides and about the y same percentage of magnesium chloride. It isthen pumped to the refineryoperation in which operation the separation of these salts in question is broughtabout.

My process will be more fully understood I by reference to the accompanying drawing illustrating diagrammatically the apparatus and system in which the refining operations are carried out. The right hand end in the present figure represents the hot end of the apparatus and the left hand end, the cold end. This apparatus comprises an indirect heater D suchas a steam Vheater' or the like, a rotary or any other suitable type of hot dissolver F, centrifugal or other typesof filters G, I, K, O, and S, a crystallizer H, a rotary cold precipitator N or any other type of precipitator and the refrigerating plant (not shown) and a cooler R.

The various parts of apparatus enumcrati yeo separated from said portion H by a metal partition 10 and divided into three separate independent compartments by means of separating Walls 11 and 12 respectively. A suitable Worm IV operates in the portion H for a purpose hereinafter specified. If desired, the crystallizer may be formed by joining three separate crystallizers end to end. Houever, the type employed is immaterial.

The solar concentrated brine, sayv of about 25 C., is passed into the outer compartment of the crystallizer at A and then travels from B to C in counter current ldirection relative to the hot brine flowing in the inner compartment H. The temperature of said brine in the compartment rises to about 60 C. From the point- C it passes through a pipe 14 to the indirect heater D, in which it is heated to about 100 Vand flows from said -heater through a pipe 15 toa point E Where it meets a mixture of sodium and potassium chloride crystals secured subsequently in the process, as Will be presently described, and suitablyv conveyed to said point. VFrom E the hot brine together with the mixed crystals is led through pipe 15 to thedissolver F, Which may be in form of a rotating drum suitably driven and which agitates the mixture. In this part of apparatus the potassium chloride is dissolved and the sodium chloride remains in crystal form. This is due to the fact that the brine dissolvesnearly 300 grams of potassium chloride at 100 C. per I1000 grams `of Water contained in the brine,-\vhereas at 25 C., only 120 grams of potassium chloride are'soluble in it. With sodium chloride the solubilities are 195 grams at y25" C. and 170 grams at 100 C. per 1000 grams of Water. The solubility of the sodium chloride, it Will, therefore, be seen, is reversed at the two respective temperatures, or

in other Words, sodium chloride is more solu- .ble at 25 C., than at 100 C. in this brine, so that a small amount of the latter 'salt actually precipitates under the higher temperature. The relative precipitation is shown diagrammatically in the drawing, wherein the potassium chloride vcrystals kare represented by small dots iY and the sodium chloride crystals by small crosses X. It Will be seen that at the right hand end of the dissolver both crystals Y and X are vpresent Whereas as the ow progresses towards the left hand end the potassium chloride crystals AY diminish in quantity.

From the dissolver F the precipitated sodium chloride crystals and brine solution while still hot are passed through the filterl G, Which may be a Ycentrifugal `iilter Yand which separates thesaid crystals from the brine solution.` The said crystals of sodium chloride maybe led to storage from said filter by any suitable conveyor 16. The brine is led from the filter G to the inner'compartment H of thecrystallizerv by pipe 17. In

said central portion the brine is gradually cooled down While heating the initial entering brine in the jacket H. During the cooling the potassium chloride begins to precipitate out because of the diering solubilities at the different temperatures above referred to. The said solution and crystals are carried through the apparatus by the rotating Worm 1V or otherwise suitably conveyed depending upon'the type of crystallizer employed.

In the next section of the crystallizer orin a separate crystallizer the hot brine is still further cooled by means of Wash Water ioW- ing into the compartment through pipe 18 and obtained from anotherportion of the process or other cooling liquors, as the brine fromV the cold precipitator. This further cooling causes further precipitation of potas- Ysium chloride crystals, which when the brine reaches the next section of the compartment H it is cooled to between010 C. by meansv of a brine coming from the cold end of the apparatus flowing into said last named seo` tion. I I

lDuring the cooling process from 100 C. to let us say, 5 C. the solubility ofpotassium chloride in the brine has beenreduced from practically 300 grams of potassium chloride per 1000' grams of Water contained in the brine to 70 grams. A precipitation of potassium chloride crystals has, therefore, taken place in keeping With these figures. The progressive increase in precipitation from the right to the left end of said crystallizer isindicated by the increasing number of crystals Y from'right to left in said prec-ipitator. The brine or suspension, While still cold is now led to the filter I, which is of the same type as filter G and the potassium chloride crystals Y are then passed by a suitable conveyor19 to the Washer K, which may be of similar type of iilter to filter G. In said Washer said crystals are Washed and freed from adhering brine and then led by means of a suitable conveyor20 to storage. The Wash Water entering said filter K through a pipe 21 is led from said filter through pipe 18 to a section of the compartment H' entering the same at L` Where it serves for cooling the oppositely flowing brine solution in the portion H of the said crystallizer, as already described. The saidwash Water mixes with other cooling liquors entering at L', as Will be hereinafter described, and the com- -bined liquors move in said outer compartment cylinder or other form of apparatus that causes stirring of the comingled brines and Where it meetsa cold brine containing a high percentage of magnesium chloride, 500 grams of magnesium chloride to 1000 grams of water. The said cold brine coming from the magnesium chloride reservoir (not shown) flows through the refrigerator (not shown) and cooler' R where it is cooled to 0o C. From said cooler R the cold brine is led through rotary filter S Where sodium and potassium crystals XandY which have precipitated out of the magnesium'chloride solution are removedfand fed to a conveyor of any suitable type which conveys said mixed Crystals to the point E for mixture with the hot brine entering the hot dissolver F. The cold brine solution emerging from filter S is led through pipe 23 to the point S where a por-4 tion of the magnesium chloride brine is led 01T to final evaporation at point T, whereby magnesium chloride crystals are'recovered.

The rest of vsaid magnesium chloride brine is led through pipe 24 to the point U of the leftsection of said crystallizer H. Thence it fiows through the-outer compartment H t'owardsrtheY right, cooling theliquid which flows through the inner compartment of the crystallizer. It then emerges from said crystallizer at point V whence it is led by pipe 25 to the entrance N of the cold precipitator N where the said magnesium chloride brine, 500 grams of magnesium chloride per 1000 gra-ms of water concentration, meets brin-e coming from the filter I and containing both' sodium and potassium chlorides in solution.

The comingled brine now contains somewhat over 300 grams ofmagnesium chloride per 1000 grams kof water at the low temperature of operation 0O C. to 10" t. The solubilities of both sodium and potassium chloride are very low, about 30 to 40 grams per 1000 grams of water for both these salts, and,

therefore, both the latter salts precipitate out in said precipitator which agitates the comingled brine to facilitate and` increase the precipitation as illustrated by the dots Y and crosses X as before.

From said precipiator N the'solution and precipitation are passed to filter O wherein the sodium and potassium crystals are re moved and fed to said conveyor 28. The cold brine leaving said filter O has a concentration of about 300 grams ofmagnesium chloride per 1000 gram of water and is led through pipe 27 to the said pointL of the outer compartment H. Th-erein it'mixes with said wash water as previously described `and cools the brine flowing in compartment H of the crystallizer. The said brine and wash water mixture is led off for further evaporation at point M from its content of approximately300 grams of magnesium chloride per 1000 grams of water to one having a content of 500 gramsand then it is Y returned to the operation and cooled in the artificial cooler R where the final small percentage of sodium and potassium chlorides This however is not essential to'secure an operative process.

During the winter months, the natural cold brine might of course be used for cooling purposes in place of the cooling artificially produced by mechanical refrigeration apparatus. Again the initial hot brine, after being freed from sodium chloride crystals, might be directlyV artificially cooled instead of by counter-current cooling for precipitation of potassium chloride. Such a step would, however, be a less efiicient one `than that initially described by me. i

The marked advantages of the processing are dependent on the use of artificial supercooling together with concentrated brine, for salting out at one end of the apparatus, and the use of hot brines at the other end for dissolving potassium chloride, and the gradual. bringing of these brines together'in such a manner that the energy utilized in heating the brines and that utilized -in cooling the same so neutralize each otheras toy bring about efficient crystallization yof potassium chloride in the intermediate steps of the process. In other words, efficient solution has beenestablished atl the hot end and efficient salting out7 at the cold end of the apparatus, and efficient crystallization in the intermediary steps. This affords very compact processing with consequent diminution of cost below the cost of the present known process.

It will be distinctly understood that artificial mechanical refrigeration is used in carrying out this processing. lIn order clearly to define our refrigeration apparatus it might be 'better to describe the same byrefrigeration means securedfrom the l mechanical compression and expansion of gases, vapors Onliquids.

What I claim 1s 1. The recovery of sodium potassium and magnesium chloride from natural brines containing these salts in aqueous solution and having'high percentage of sodium chloride, comprising the steps of first evaporating said brine by solar heat to a point Where the brine becomes saturated with potassium chloride and the greater percentage of sodium chloride has been precipitated out and the greater Y of about 500 grams per 1000 grams of water and artificially'cooled to between 5 and 5 C. by utilizing the compression and expansion of fluids for the production of cold, then filtering oft' the sodium` and potassium chloride crystals precipitated from the said treatment, then evaporating the comingled brines `to substantially the: original magnesium chloride concentration, then artificially cooling to between 5 and *5 C. by utilizing the compression and expansion of fluids for the production of cold the latter brines for precipitating the residual sodium and potassium chloride crystals therein contained, thenfiltering ofl:` the latter salt crystals and securing crystalline magnesium chloride vby further evaporation of .the said concentrated brine. y

2. The recovery of sodium potassium and magnesium chlorides from natural brines containing these salts in aqueous solution and having a highV percentage of sodium chloride, comprising the steps of first evaporating said brine by solar heat to a point where the brine becomes saturated with potassium 'chloride and the greater percentage of sodium chloride has been precipitated out and the great'- er percentage ofvvater evaporated, then heating the 'solar concentrated brine saturated as yto potassiumchlorideat the normal atmospliericI temperature', for solution of an increasedv percentage of potassium chloride, soluble at a higher temperature, from a mixture of sodium and potassium chlorides subsequently obtained in the process, then filteringlofi the undissolved sodium chloride, then artificially cooling the brinesto between 5 and- C. by application of counter current cooling action secured from other brines subsequently produced in theprocess vand artificially cooled to between 5and '--5 C., by utilizing the compression and expansion of fluids for the production of' cold then filtering oflthe precipitated potassium chloride, ,then mixing the residual brine with the brine A subsequently obtained in the' process and artificially cooled to between 5 andY V-5 C., by utilizing the compression and 'expansion of fluids for theproduction of cold, land containing magnesium Vchloride yin concentration of about 500 grams per`1000 grams of water, then filtering off the sodium and potassium chloride crystals precipitated by the said treatment, 'then' evaporating the comingled brines yto substantially the original magnesium chloride concentration, then artificially cooling to between -'5 and 5 C. utilizing the compression andexpansion of fluids for zthe production of cold the latter brines'pfor' precipitating the residual sodium and potassium chloride crystals therein contained, then filtering off the latter salt crystalsiand utilizing part of the artificially cooled high percentage magnesium chloride f containing brines for cooling olf the aforementioned hot brines used in the process and employing another part for securing crystalline magnesium chloride by Jfurther evaporation.

3. The recovery of sodium, potassium and magnesium chlorides from natural brines containing these salts in aqueous solution,` and from brines more especiallyl containing a relatively higher percentage of sodium chloride, by first evaporating the said brine by solar heat to a point at whichthe brine becomes saturated with potassium chloride and 80% to 90% ot the sodium chloride has beenfprecipitated outA and 80% to 90% of the water evaporated, then heating of the latter solar concentrated brine, saturatedwith and containing about 120 grams of potassium chloride to 1000 grams of water at C. for further solution at 100 C. in the said brine of potassium chloride up to 300 grams per 1000 gramsof v water-from amixture of sodium and potassium chlorides,subsequently obtained inthe process, filtering off the undissolved sodium chloride,cooling of! the Ibrine to from 5 to 15 C. by artificial cooling, as by application'of counter-current cooling action secured from other brines subsequently produced in the process and artificially cooled to from 5"v to 5 C., filtering off the*precipitated-potassium chloride, mixing the -brine with a brine subsequently obtained in the process and artificially cooled to about 0 C., and containing about 500 grams of magnesium chloride per 1000 grams of water, filtering off `the sodium and potassium chloride crystals precipitated, 'for treatment by the hot brine as aforementioned, evaporating the comingled brines containing about 300 grams of magnesium chloride per 1000 grams of water to substantially Y the original magnesium chloride content aforementioned, artificially coo'ling to0 C. i120 thelatter brine for precipitating the residual sodium and potassium chloride crystals therein contained, filtering oli ,the latter Asalt crystalsv and utilizing part of said artificially cooled high percentage magnesium chloride brine for cooling of the aforementioned hot brine used in theprocess and employing another part thereof to secure crystalline magnesium chloride by further evaporation.

4. The recoveryof sodium, potassium and magnesium chlorides from natural brines containing these salts in aqueous solution and having a high percentage of sodium chloride, comprising the steps of lirst evaporating said brine to a point Where the latter becomes saturated With potassium chloride and the greater percentage of sodium chloride has been precipitated out and the greater percentage of Water evaporated, then heating the concentrated brine, saturated as to potassium chloride at normal atmospheric temperature, for solution of an increased percentage of potassium chloride from a mixture of sodium and potassium chlorides subsequently obtained in the process, then iiltering 0E the undissolved sodium chloride, then cooling the brines to about between 5 and 15 C., then liltering olf the precipitated potassium chloride, then mixing the residual brine With a brine subsequently obtained in the process which has been articially cooled to about 0 C. and which contains a high percentage of magnesium chloride, then filtering off the sodium and potassium chloride crystals precipitated from said latter treatment, then evaporating the comingled brines to a high percentage of magnesium chloride content and then artificially cooling the latter brines to from 5 to 5 C. for precipitation of the residual sodium and potassium chloride crystals and securing crystalline magnesium chloride by further evaporation of said concentrated brine.

In testimony whereof I affix my signature.

HERMAN B. KIPPER. 

